Abstract : A procedure is developed for determining a time on site for non-firing indirect fire systems to maximize the probability of surviving without attack through a sequence of moves and on-site periods comprising an arbitrarily long time. While the model was originally developed for application to indirect fire weapons systems, it is applicable to any non-firing system including command posts, supply points, and non-engaged units. Application of the model requires input data on the probabilities of detection and attack while the system is on site (hiding) and while it is moving between sites. Based on data associated with these probabilities, an optimum time on site (which maximizes the probability of surviving without attack) is determined. The model is structured to facilitate application to a set of systems located at various distances behind the FEBA.